This invention relates to anchoring pins of the type which are screw threaded into the maxilla bone of a patient, for the implantation of a dental prosthesis.
At present, self-threading conical shaped pins are used, which are screw threaded into the maxilla bone. For this purpose it is necessary to make a bore of a suitable size into the maxilla bone. If this bore is too small, during the screwing of the self-threading pin tensions may be created tending to deform the maxilla bone. If this bore is too large, the fastening of the pin is unstable. In both instances, by taking into account the forces to which the pin is subjected during mastication, a progressive weakening of the fastening of the pin to the maxilla bone very often occurs.
The present invention aims to eliminate the above described drawbacks of the prior art anchoring pins.
According to one feature of the invention, this aim is obtained by means of a self-threading pin comprising a drill or cutter shaped bit portion at one end, a substantially cylindrical, screw threaded shank portion and a driving head at the opposite end. By screwing the pin into a previously drilled bore in the maxilla bone, the drilling bit of the pin excavates a seat of a diameter corresponding to or otherwise fitting the cylindrical screw threaded shank of the pin, thus avoiding the danger of internal tensions as well as the danger of an unstable fastening of the pin. Or, stated differently, the drill bit has an effective cutting diameter substantially equal to the land areas of the intermediate shank portion of the pin. The thus obtained fastening is therefore optimal and this will result in a greater resistance of the pin to the stresses to which it is subjected during mastication, without progressively impairing the solidity of the fastening to the maxilla bone and thus assuring a longer duration of the dental prosthesis carried by the said pin.